In a power device using silicon (Si), a low on-resistance around a limit of Si is realized. In order to further improve a breakdown voltage and to reduce an on-resistance, a material used for the power device is preferably changed.
By using a nitride semiconductor such as GaN or AlGaN, a trade-off relationship depending on a semiconductor material can be improved, and therefore a dramatically high breakdown voltage of the power device and reduction of a low on-resistance thereof can be achieved.